Problem: Simplify the following expression: $k = \dfrac{r - 6q}{2p + 4} - \dfrac{2p - 6q}{2p + 4}$ You can assume $p,q,r \neq 0$.
Explanation: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{r - 6q - (2p - 6q)}{2p + 4}$ $k = \dfrac{r - 2p}{2p + 4}$